# Find hte sum of series

1. Feb 8, 2007

### rcmango

1. The problem statement, all variables and given/known data

heres the equation: http://img255.imageshack.us/img255/1669/untitledfa5.jpg [Broken]

2. Relevant equations

i think we use cos(x)

3. The attempt at a solution

i know that cos(x) = cos(pi)

so the limit is -1?

whats the sum, i'm a bit confused.
must be in simplest form
what must i show. help.

Last edited by a moderator: May 2, 2017
2. Feb 8, 2007

### Dick

I don't think you can express the sum much more simply than -1. The 'limit' you are talking about is the 'sum', right?

3. Feb 8, 2007

### arildno

What you must show is that the infinite series representation of $\cos(\pi)$ is identical to the infinite series given in the exercise.

4. Feb 8, 2007

### rcmango

excellent, okay ya its simple it is only -1. I just wasn't sure what they wanted to see. thanks